Drive and control system in sewing machines producing groups of stitches

ABSTRACT

The present invention is a pneumatically actuated control system for sewing machines to begin and end the sewing cycle and simultaneously to place and retain the work clamp or presser foot into proper relationship with the material during the sewing cycle and comprises a first pneumatic circuit of a control valve, adjustable inlet valve and exhaust valve which circuit is mechanically linked to the sewing cycle control element in the sewing machine and a second pneumatic circuit of a first control valve, a second control valve actuated by the mechanical linkage of the first circuit, a third control valve actuated by the work clamp control element in the sewing machine, an adjustable inlet valve, and an exhaust valve which second circuit is mechanically linked to the work clamp and means to selectively actuate the control valve of the first circuit and the first control valve of the second circuit.

United States Patent Bianchi [54] DRIVE AND CONTROL SYSTEM IN SEWING MACHINES PRODUCING GROUPS OF STITCHES Nereo Bianchi, Pavia, Italy [73] Assignee: Necchi S.p.A., Pavia, Italy [22] Filed: Apr. 23, 1970 [21] Appl. No.: 31,252

[72] Inventor:

[30] Foreign Application Priority Data Apr. 23, 1969 Italy ..324l0 A/69 [52] U.S.Cl

[ June 6, 1972 Primary Examiner-+1. Hampton Hunter Attorney-Stevens, Davis, Miller & Mosher [57] ABSTRACT The present invention is a pneumatically actuated control system for sewing machines to begin and end the sewing cycle and simultaneously to place and retain the work clamp or presser foot into proper relationship with the material during the sewing cycle and comprises a first pneumatic circuit of a control valve, adjustable inlet valve and exhaust valve which circuit is mechanically linked to the sewing cycle control element in the sewing machine and a second pneumatic circuit of a first control valve, a second control valve actuated by the mechanical linkage of the first circuit, a third control valve actuated by the work clamp control element in the sewing machine, an adjustable inlet valve, and an exhaust valve which second circuit is mechanically linked to the work clamp and means to selectively actuate the control valve of the first circuit and the first control valve of the second circuit.

1 Claims, 8 Drawing Figures PATENTEUJUH 6 I972 SHEET 10F FIG.

INVENTOR NEREO B/ANCHI of? W ATTORNEYS DRIVE AND CONTROL SYSTEM IN SEWING MACHINES PRODUCING GROUPS OF STITCHES The present invention refers to a drive and control system in sewing machineswhich produces groups of stitches which includes pneumatically driven means to automatically control the beginning and ending of the sewing cycle and the lifting and lowering of the work clamp or presser foot.

The important operating features required of such drive and control systems are the lowering of the work clamp before beginning the sewing cycle and the lifting thereof after the end of said cycle so that no stitches are made when the work clamp is lifted, and avoiding the repetition of the sewing cycle on the same workpiece when the operator delays in releasing the starting treadle.

'- Sewing machines producing groups of stitches are already well known in the art and are provided with drive and control systems adapted to provide the operating features mentioned above. Nevertheless, these known systems require the use of special members which are rather expensive and therefore greatly affect the sale prices of the sewing units on which they are mounted. The present invention is a pneumatic drive system which operates in a reliable manner and at the same time is simple in its design and functioning and inexpensive to construct.

The technical problem to be solved was that of incorporating simple and inexpensive members into the existing drive system circuit in such a way as to provide the performance and the reliability required. The solution of the technical problem is achieved by providing an adjustable inlet valve and a quick exhaust valve within the pneumatic circuit which valves are connected in series with each of the we drive cylinders provided to cause the starting of the machine and the lowering and lifting of the work clamp.

The drive and control system of the present invention will now be described according to an embodiment which is illustrative of the invention and non-limiting, and with reference to the accompanying drawings in which:

FIG. 1 shows schematically the drive and control system in a buttonhole sewing machine in which the present invention is incorporated;

FIGS. 2-6 show the pneumatic circuits of the system of FIG. 1 during the different phases of the sewing cycle in which the solid black lines depict the flow of air to actuate the different elements of the machine, wherein p FIG. 2 is a schematic presentation of the invention at the end of the sewing cycle;

FIG. 3 is a schematic presentation of the invention just prior to the start of thesewing cyclej FIG. 4 is aschematic presentation of the invention atthe start of the sewing cycle;

FIG. 5 is a schematic presentation of the sewing cycle;

FIG. 6 is a schematic presentation of the invention when the sewing cycle is interrupted;

FIG. 7 shows schematically, the exhaust valve of the invention in an open condition;

FIG. 8 shows schematically the valve of FIG. 7 in the exhaust condition.

Referring to FIG. 1, the sewing machine of the type producing groups of stitches for buttonholes is schematically shown and indicated as 10. The machine comprises a bed 11, a standard 12, a horizontal arm 13 overhanging the bed 11. The work table 14 is provided for mounting the machine the invention during thereon.

The particular pneumatic drive and control system for the machine comprises a filter 15, a pressure gauge 16 and a lubricator 17 inserted adjacent the inlet of the main feed line. Two three-way valves 18 and 19 are inserted in parallel in the pneumatic circuit downstream of the lubricator 17 and are altematively actuated by a rod 20 pivoted at one end on a pin 21 and connected by link 22 to a treadle 23 pivoted about pin 24 on mounting 25. The first three-way valve 18 is connected by means of conduit 26 with a needle valve 27 of the invention placed in series with the quick exhaust valve 28 of the invention which is connected with a pneumatic piston cylinder 29. The operating rod 29' of the cylinder 29 is operatively connected to a bent arm lever 30 pivotally mounted about a pin 31, to act upon one arm of the multi-arm lever 32 which in turn is pivoted about pin 33. As shown in FIGS. 2-6, the lever 32 has a second arm 32' carrying a projection 47 at its end which engages a tooth 34 of the handwheel 35 of the sewing machine as schematically shown in FIGS. 2-6. A third arm 32" of said lever acts on a first two-.way valve 36 which is connected at one end by means of conduit 37 with the second three-way valve 19. Valve 36 is connected at the opposite end by conduit 38 with a second two-way valve 39 which is operated by a cam 40 provided in the machine and suitably timed relative to its rotation cycle. As best shown in FIGS. 2-4, valve 39 is also connected by means of a conduit 41 to another needle valve 42 in series with another quick exhaust valve 43 which is connected with another pneumatic cylinder 44 similar to cylinder 29. Cylinder 44 is operatively connected to a lever 46 pivotally mounted in the machine for lifting and lowering the work clamp 45.

Sewing machine drive members are shown in FIG. 2 in the position at the completion of the sewing cycle. Treadle 23 is up and rod 20 acts on valve 19 keeping it open. From valve 19 compressed air flows through conduit 37 to valve 36, which is kept open by arm 32" of the lever 32, said lever forming by its projection 47, and together with tooth 34, a lock for the machine. By means of conduit 38 which connects valve 36 with valve 39, compressed air reaches said valve 39 which is kept open by cam 40. From valve 39, through conduit 41, compressed air passes through needle valve 42 and quick exhaust valve 43 to cylinder 44 which moves downward and thus actuates the lifting of work clamp 45 by means of lever 46.

When treadle 23 is in the intermediate @sition shown in FIG. 3, rod 20 is not in engagement with valve 19 which then closes, thus interrupting the air flow to cylinder 44. This interruption allows the pressurized air in said cylinder 44 to vent through quick exhaust valve 43 thus causing lowering of arm 46 which is connected to work clamp 45. At this point of the cycle the clamp can be lifted in order to position or to reposition the fabric to be sewn, without having to effect particular maneuvers. For this it is only necessary to release the treadle which returns, under the bias of a suitable spring (not shown in the drawings) to the position of FIG. 2. Thus valve 19 is opened again and compressed air flows to cylinder 44 operating the arm 46 raising the work clamp 45.

By pressing treadle 23 further down as shown in FIG. 4, rod 20 opens valve 18 and compressed air, through conduit 26, needle valve 27 and quick exhaust valve 28, enters cylinder 29. The actuation of cylinder 29 causes rotation of lever 30 about pin 31 and the consequent rotation of levers 32 about pin 33. Said lever 32, because of its rotation, disengages projection 47 from tooth 34 of handwheel 35 and the machine begins its sewing cycle. Lever 32, by its rotation causes the closing of valve 36 which shuts off conduit 38.

In spite of releasing treadle 23 as shown in -FIG. 5, the machine will continue sewing. Rod 20 is no longer in contact with valve 18 which closes thus interrupting the air flow to cylinder 29. Therefore, the pressurized air stored in cylinder 29 vents through quick exhaust valve 28, and lever 30 is returned to its starting position. Thus the rotation of lever 32, at the end of the sewing cycle, by usual means provided on the machine will cause the engagement of projection 47 with tooth 34 in order to lock the machine. During the sewing cycle, after release of treadle 23 by the operator, valve 19, being in contact with rod 20, is opened and the air flow passing through conduit 37 reaches valve 36 which however is closed as described above because it is not actuated by the arm 32" of lever 32. At the end of the sewing cycle, machine locking takes place automatically owing to the rotation of lever 32 previously described which causes projection 47 on arm 32" to engage tooth 34. At the same time, arm 32" of said lever 32 opens valve 36 while cam 40, having completed its rotational cycle, simultaneously opens valve 39 whereby compressed air passes through conduit 41 to actuate cylinder 44 which in turn, by means of lever 46, lifts work clamp 45. Thus the circuit conditions of FIG. 2 are re-established.

If, during sewing,'a break should occur, such as the upper thread breaking, manual operation of the usual emergency stop device independently causes rotation of lever 32 whereby projection 47 of said lever 32 (FIG. 6) engages tooth 34 of handwheel 35 thus causing the machine to lock against further sewing. In this instance valve 36 will be opened by arm 32" of said lever 32 and air passes through conduit 38 to valve 39. The valve is closed as described with reference to FIG. 2 and it is opened only by cam 40 at the end of every sewing cycle. Since valve 36 is closed air cannot flow into cylinder 44. In this manner the raising of work clamp 45 is prevented making it possible to resume sewing at the same point at which it has been interrupted.

Needle valve 27 and 42 used in the pneumatic circuit above described allow for the adjustment of the compressed air flow therethrough by use of a suitable member provided to adjust the flow port.

Quick exhaust valves 28 and 43 have the shape schematically shown in FIGS. 7 and 8 wherein they are shown in the open and exhaust positions respectively. An inlet port 50 is provided having its diameter smaller than the diameter of the outlet ports 51, 52. Outlet port 51 leads to cylinder 29 or 44. During the intervals when air is flowing into the valve from conduit 27 or 41, sealing member 49 is urged by the compressed air against the inner end of exhaust port 52 and closes it thus directing the air into cylinder 29 or 44. To establish the quick exhaust phase, when air is no longer flowing in through port 50, member 49 is biased by spring 48 against the inner end of the inlet port 50, closing it and opening exhaust port 52 to the atmosphere.

From what has been described it is clear that, by using needle valve 42 which has been suitably calibrated and quick exhaust valve 43 placed at the inlet of cylinder 44, cylinder 44 will lower the work clamp shortly before the sewing cycle begins (FIG. 3), owing to the quick exhaust of the air through exhaust port 52 of valve 43, and to effect a delay in the lifting of the work clamp by means of a suitable adjustment of needle valve 42 at the end of the sewing cycle. Undesirable movement of the work clamp can also be prevented by the use of quick exhaust valve 28 at the inlet of cylinder 29 which allows the cylinder to quickly displace lever 30 into the lock position of FIG. 5. In this way the initiation of a new sewing cycle is avoided if the operator delays releasing treadle 23 after the starting of the sewing cycle as described with reference to FIG. above. At the same time needle valve 27, when suitably adjusted, is used for delaying the starting of the sewing cycle which is determined by cylinder 29 in correlation with the lowering of the work clamp.

Safety systems as described above, which are suitable to allow the predetermined sequence of the work clamp lowering and raising relative to the starting or stopping of the operating cycle, could seem useless in the cycle starting phase, if the operator would control lowering of treadle 23 to the two positions shown in FIGS. 3 and 4 and allow a certain time interval between the two movements. However, this does not take place normally, because when the operator has acquired a certain experience in the work, the operations are carried out in quick succession.

What is claimed is:

1. In a sewing machine for producing a group of stitches of the time type and having an element to control the beginning and ending of the sewing cycle and cam means to cyclically control the lowering and raising of the work clamp which holds the material to be sewn in a predetermined position during the sewing cycle, a first pneumatic circuit comprising a conduit leading from a source of compressed air to a first piston assembly, a plurality of levers operatively associated with said first piston assembly to selectively engage said sewing cycle control element, a second pneumatic circuit comprising a second piston assembly and three interconnected conduits leading from said source of compressed air to said second piston assembly, means operatively connecting said second piston assembly to said work clamp to move said clamp in response to the direction of flow of air in said second circuit, a control valve in each circuit adjacent said source of compressed air to open and close each circuit to the flow of said air to the respective piston assembly, a common means to selectively operate each of said control valves, a first valve in said second circuit interconnecting the first and second conduits and adapted to be actuated by a said lever to control the flow of air between said first and second conduits and a second valve in said second circuit interconnecting the second and third conduits of said second circuit and leading to said second piston assembly and adapted to be actuated by the cyclic movement of said cam, said second valve comprising means to control the flow of air from said second conduit through said third conduit to said second piston assembly, wherein said first piston assembly is pivotally connected to the end of one arm of a first of said levers which is mounted in a swiveled manner in said sewing machine, the other arm of said first lever being in contact with one arm of a second of said levers pivotally mounted in said machine above said first lever, a second arm of said second lever extends upwardly from said pivotal mounting, means on this last mentioned second arm to lockingly engage said sewing cycle control element, and a third arm of said second lever extends laterally from said first and second arms into operative contact with the first valve of said second pneumatic circuit when the second arm of the second lever lockingly engages said sewing cycle control element. 

1. In a sewing machine for producing a group of stitches of the time type and having an element to control the beginning and ending of the sewing cycle and cam means to cyclically control the lowering and raising of the work clamp which holds the material to be sewn in a predetermined position during the sewing cycle, a first pneumatic circuit comprising a conduit leading from a source of compressed air to a first piston assembly, a plurality of levers operatively associated with said first piston assembly to selectively engage said sewing cycle control element, a second pneumatic circuit comprising a second piston assembly and three interconnected conduits leading from said source of compressed air to said second piston assembly, means operatively connecting said second piston assembly to said work clamp to move said clamp in response to the direction of flow of air in said second circuit, a control valve in each circuit adjacent said source of compressed air to open and close each circuit to the flow of said air to the respective piston assembly, a common means to selectively operate each of said control valves, a first valve in said second circuit interconnecting the first and second conduits and adapted to be actuated by a said lever to control the flow of air between said first and second conduits and a second valve in said second circuit interconnecting the second and third conduits of said second circuit and leading to said second piston assembly and adapted to be actuated by the cyclic movement of said cam, said second valve comprising means to control the flow of air from said second conduit through said third conduit to said second piston assembly, wherein said first piston assembly is pivotally connected to the end of one arm of a first of said levers which is mounted in a swiveled manner in said sewing machine, the other arm of said first lever being in contact with one arm of a second of said levers pivotally mounted in said machine above said first lever, a second arm of said second lever extends upwardly from said pivotal mounting, means on this last mentioned second arm to lockingly engage said sewing cycle control element, and a third arm of said second lever extends laterally from said first and second arms into operative contact with the first valve of said second pneumatic circuit when the second arm of the second lever lockingly engages said sewing cycle control element. 